#!/bin/bash
# @Function
# Find out the highest cpu consumed threads of java processes, and print the stack of these threads.
#
# @Usage
#   $ ./show-busy-java-threads
#
# @online-doc https://github.com/oldratlee/useful-scripts/blob/dev-2.x/docs/java.md#-show-busy-java-threads
# @author Jerry Lee (oldratlee at gmail dot com)
# @author superhj1987 (superhj1987 at 126 dot com)
#
# NOTE about Bash Traps and Pitfalls:
#
# 1. DO NOT combine var declaration and assignment which value supplied by subshell!
#    for example: readonly var1=$(echo value1)
#                 local var1=$(echo value1)
#
#    declaration make exit code of assignment to be always 0,
#      aka. the exit code of command in subshell is discarded.
#      tested on bash 3.2.57/4.2.46

# NOTE: DO NOT declare var PROG as readonly, because its value is supplied by subshell.
PROG="$(basename "$0")"
readonly PROG_VERSION='2.5.0-dev'
# choosing between $0 and BASH_SOURCE
# https://stackoverflow.com/a/35006505/922688
# How can I get the source directory of a Bash script from within the script itself?
# https://stackoverflow.com/questions/59895
# Will $0 always include the path to the script?
# https://unix.stackexchange.com/questions/119929
readonly -a COMMAND_LINE=("${BASH_SOURCE[0]}" "$@")
# Get current user name via whoami command
#   See https://www.lifewire.com/current-linux-user-whoami-command-3867579
# Because if run command by `sudo -u`, env var $USER is not rewritten/correct, just inherited from outside!
#
# NOTE: DO NOT declare var USER as readonly, because its value is supplied by subshell.
USER="$(whoami)"

################################################################################
# util functions
################################################################################

# NOTE: $'foo' is the escape sequence syntax of bash
readonly ec=$'\033'      # escape char
readonly eend=$'\033[0m' # escape end
readonly nl=$'\n'        # new line

colorEcho() {
    local color=$1
    shift

    # if stdout is console, turn on color output.
    [ -t 1 ] && echo "${ec}[1;${color}m$*$eend" || echo "$@"
}

colorPrint() {
    local color=$1
    shift

    colorEcho "$color" "$@"
    [[ -n "$append_file" && -w "$append_file" ]] && echo "$@" >>"$append_file"
    [[ -n "$store_dir" && -w "$store_dir" ]] && echo "$@" >>"${store_file_prefix}$PROG"
}

# shellcheck disable=SC2120
normalPrint() {
    echo "$@"
    [[ -n "$append_file" && -w "$append_file" ]] && echo "$@" >>"$append_file"
    [[ -n "$store_dir" && -w "$store_dir" ]] && echo "$@" >>"${store_file_prefix}$PROG"
}

redPrint() {
    colorPrint 31 "$@"
}

greenPrint() {
    colorPrint 32 "$@"
}

yellowPrint() {
    colorPrint 33 "$@"
}

bluePrint() {
    colorPrint 36 "$@"
}

die() {
    redPrint "Error: $*" 1>&2
    exit 1
}

logAndRun() {
    echo "$@"
    echo
    "$@"
}

logAndCat() {
    echo "$@"
    echo
    cat
}

# Bash RegEx to check floating point numbers from user input
# https://stackoverflow.com/questions/13790763
isNonNegativeFloatNumber() {
    [[ "$1" =~ ^[+]?[0-9]+\.?[0-9]*$ ]]
}

isNaturalNumber() {
    [[ "$1" =~ ^[+]?[0-9]+$ ]]
}

isNaturalNumberList() {
    [[ "$1" =~ ^([0-9]+)(,[0-9]+)*$ ]]
}

# print calling(quoted) command line which is able to copy and paste to rerun safely
#
# How to get the complete calling command of a BASH script from inside the script (not just the arguments)
# https://stackoverflow.com/questions/36625593
printCallingCommandLine() {
    local arg isFirst=true
    for arg in "${COMMAND_LINE[@]}"; do
        if $isFirst; then
            isFirst=false
        else
            printf ' '
        fi
        printf '%q' "$arg"
    done
    echo
}

usage() {
    local -r exit_code="${1:-0}"
    (($# > 0)) && shift
    # shellcheck disable=SC2015
    [ "$exit_code" != 0 ] && local -r out=/dev/stderr || local -r out=/dev/stdout

    (($# > 0)) && colorEcho 31 "$*$nl" >$out

    cat >$out <<EOF
Usage: ${PROG} [OPTION]... [delay [count]]
Find out the highest cpu consumed threads of java processes,
and print the stack of these threads.

Example:
  ${PROG}       # show busy java threads info
  ${PROG} 1     # update every 1 second, (stop by eg: CTRL+C)
  ${PROG} 3 10  # update every 3 seconds, update 10 times

Output control:
  -p, --pid <java pid(s)>   find out the highest cpu consumed threads from
                            the specified java process.
                            support pid list(eg: 42,47).
                            default from all java process.
  -c, --count <num>         set the thread count to show, default is 5.
                            set count 0 to show all threads.
  -a, --append-file <file>  specifies the file to append output as log.
  -S, --store-dir <dir>     specifies the directory for storing
                            the intermediate files, and keep files.
                            default store intermediate files at tmp dir,
                            and auto remove after run. use this option to keep
                            files so as to review jstack/top/ps output later.
  delay                     the delay between updates in seconds.
  count                     the number of updates.
                            delay/count arguments imitates the style of
                            vmstat command.

jstack control:
  -s, --jstack-path <path>  specifies the path of jstack command.
  -F, --force               set jstack to force a thread dump.
                            use when jstack does not respond (process is hung).
  -m, --mix-native-frames   set jstack to print both java and
                            native frames (mixed mode).
  -l, --lock-info           set jstack with long listing.
                            prints additional information about locks.

CPU usage calculation control:
  -i, --cpu-sample-interval specifies the delay between cpu samples to get
                            thread cpu usage percentage during this interval.
                            default is 0.5 (second).
                            set interval 0 to get the percentage of time spent
                            running during the *entire lifetime* of a process.

Miscellaneous:
  -h, --help                display this help and exit.
  -V, --version             display version information and exit.
EOF

    exit "$exit_code"
}

progVersion() {
    echo "$PROG $PROG_VERSION"
    exit
}

################################################################################
# Check os support
################################################################################

uname | grep '^Linux' -q || die "$PROG only support Linux, not support $(uname) yet!"

################################################################################
# parse options
################################################################################

# NOTE: ARGS can not be declared as readonly!!
# readonly declaration make exit code of assignment to be always 0, aka. the exit code of `getopt` in subshell is discarded.
#   tested on bash 4.2.46
ARGS=$(
    getopt -n "$PROG" -a -o c:p:a:s:S:i:Pd:FmlhV \
        -l count:,pid:,append-file:,jstack-path:,store-dir:,cpu-sample-interval:,use-ps,top-delay:,force,mix-native-frames,lock-info,help,version \
        -- "$@"
) || {
    echo
    usage 1
}
eval set -- "${ARGS}"

count=5
cpu_sample_interval=0.5

while true; do
    case "$1" in
    -c | --count)
        count="$2"
        shift 2
        ;;
    -p | --pid)
        pid_list="$2"
        shift 2
        ;;
    -a | --append-file)
        append_file="$2"
        shift 2
        ;;
    -s | --jstack-path)
        jstack_path="$2"
        shift 2
        ;;
    -S | --store-dir)
        store_dir="$2"
        shift 2
        ;;
    # support the option name -P,--use-ps for compatibility
    -P | --use-ps)
        cpu_sample_interval=0
        shift
        ;;
    # support the option name -d,--top-delay for compatibility
    -i | --cpu-sample-interval | -d | --top-delay)
        cpu_sample_interval="$2"
        shift 2
        ;;
    -F | --force)
        force=-F
        shift
        ;;
    -m | --mix-native-frames)
        mix_native_frames=-m
        shift
        ;;
    -l | --lock-info)
        more_lock_info=-l
        shift
        ;;
    -h | --help)
        usage
        ;;
    -V | --version)
        progVersion
        ;;
    --)
        shift
        break
        ;;
    esac
done

update_delay=${1:-0}
isNonNegativeFloatNumber "$update_delay" || die "update delay($update_delay) is not a non-negative float number!"

[ -z "$1" ] && update_count=1 || update_count=${2:-0}
isNaturalNumber "$update_count" || die "update count($update_count) is not a natural number!"

if [ -n "$pid_list" ]; then
    pid_list="${pid_list//[[:space:]]/}" # delete white space
    isNaturalNumberList "$pid_list" || die "pid(s)($pid_list) is illegal! example: 42 or 42,99,67"
fi

# check the directory of append-file(-a) mode, create if not exist.
if [ -n "$append_file" ]; then
    if [ -e "$append_file" ]; then
        [ -f "$append_file" ] || die "$append_file(specified by option -a, for storing run output files) exists but is not a file!"
        [ -w "$append_file" ] || die "file $append_file(specified by option -a, for storing run output files) exists but is not writable!"
    else
        append_file_dir="$(dirname "$append_file")"
        if [ -e "$append_file_dir" ]; then
            [ -d "$append_file_dir" ] || die "directory $append_file_dir(specified by option -a, for storing run output files) exists but is not a directory!"
            [ -w "$append_file_dir" ] || die "directory $append_file_dir(specified by option -a, for storing run output files) exists but is not writable!"
        else
            mkdir -p "$append_file_dir" || die "fail to create directory $append_file_dir(specified by option -a, for storing run output files)!"
        fi
    fi
fi

# check store directory(-S) mode, create directory if not exist.
if [ -n "$store_dir" ]; then
    if [ -e "$store_dir" ]; then
        [ -d "$store_dir" ] || die "$store_dir(specified by option -S, for storing output files) exists but is not a directory!"
        [ -w "$store_dir" ] || die "directory $store_dir(specified by option -S, for storing output files) exists but is not writable!"
    else
        mkdir -p "$store_dir" || die "fail to create directory $store_dir(specified by option -S, for storing output files)!"
    fi
fi

isNonNegativeFloatNumber "$cpu_sample_interval" || die "cpu sample interval($cpu_sample_interval) is not a non-negative float number!"

################################################################################
# search/check the existence of jstack command
#
# search order/priority:
#    1. from -s option
#    2. from under env var JAVA_HOME
#    3. from under env var PATH
################################################################################

if [ -n "$jstack_path" ]; then
    # 1. check jstack_path set by -s option
    [ -f "$jstack_path" ] || die "$jstack_path (set by -s option) is NOT found!"
    [ -x "$jstack_path" ] || die "$jstack_path (set by -s option) is NOT executable!"
elif [ -n "$JAVA_HOME" ]; then
    # 2. search jstack under JAVA_HOME
    if [ -f "$JAVA_HOME/bin/jstack" ]; then
        [ -x "$JAVA_HOME/bin/jstack" ] || die "found \$JAVA_HOME/bin/jstack($JAVA_HOME/bin/jstack) is NOT executable!${nl}Use -s option set jstack path manually."
        jstack_path="$JAVA_HOME/bin/jstack"
    elif [ -f "$JAVA_HOME/../bin/jstack" ]; then
        [ -x "$JAVA_HOME/../bin/jstack" ] || die "found \$JAVA_HOME/../bin/jstack($JAVA_HOME/../bin/jstack) is NOT executable!${nl}Use -s option set jstack path manually."
        jstack_path="$JAVA_HOME/../bin/jstack"
    fi
elif command -v jstack &>/dev/null; then
    # 3. search jstack under PATH
    jstack_path="$(command -v jstack)"
    [ -x "$jstack_path" ] || die "found $jstack_path from PATH is NOT executable!${nl}Use -s option set jstack path manually."
else
    die "jstack NOT found by JAVA_HOME(${JAVA_HOME:-not set}) setting and PATH!${nl}Use -s option set jstack path manually."
fi

################################################################################
# biz logic
################################################################################

# NOTE: DO NOT declare var run_timestamp as readonly, because its value is supplied by subshell.
run_timestamp="$(date "+%Y-%m-%d_%H:%M:%S.%N")"
readonly uuid="${PROG}_${run_timestamp}_${$}_${RANDOM}"

readonly tmp_store_dir="/tmp/${uuid}"
if [ -n "$store_dir" ]; then
    readonly store_file_prefix="$store_dir/${run_timestamp}_"
else
    readonly store_file_prefix="$tmp_store_dir/${run_timestamp}_"
fi
mkdir -p "$tmp_store_dir"

cleanupWhenExit() {
    rm -rf "$tmp_store_dir" &>/dev/null
}
trap cleanupWhenExit EXIT

headInfo() {
    colorEcho "0;34;42" ================================================================================
    echo "$(date "+%Y-%m-%d %H:%M:%S.%N") [$((update_round_num + 1))/$update_count]: $(printCallingCommandLine)"
    colorEcho "0;34;42" ================================================================================
    echo
}

if [ -n "${pid_list}" ]; then
    readonly ps_process_select_options="-p $pid_list"
else
    readonly ps_process_select_options="-C java -C jsvc"
fi

__die_when_no_java_process_found() {
    if [ -n "${pid_list}" ]; then
        die "process($pid_list) is not running, or not java process!"
    else
        die 'No java process found!'
    fi
}

# output field: pid, thread id(lwp), pcpu, user
#   order by pcpu(percentage of cpu usage)
#
# NOTE:
# use ps command to find busy thread(cpu usage)
# cpu usage of ps command is expressed as
# the percentage of time spent running during the *entire lifetime* of a process,
# this is not ideal in general.
findBusyJavaThreadsByPs() {
    # 1. sort by %cpu by ps option `--sort -pcpu`
    #    unfortunately, ps from `procps-ng 3.3.12`, `--sort` does not work properly with other options,
    #    use
    #       ps <other options>
    #    combined
    #       sort -k3,3nr
    #    instead of
    #       ps <other options> --sort -pcpu
    # 2. use wide output(unlimited width) by ps option `-ww`
    #    avoid trunk user column to username_fo+ or $uid alike

    # shellcheck disable=SC2206
    local -a ps_cmd_line=(ps $ps_process_select_options -wwLo 'pid,lwp,pcpu,user' --no-headers)
    # DO NOT combine var ps_out declaration and assignment, because its value is supplied by subshell.
    local ps_out
    ps_out="$("${ps_cmd_line[@]}" | sort -k3,3nr)"
    [ -n "$ps_out" ] || __die_when_no_java_process_found

    if [ -n "$store_dir" ]; then
        echo "$ps_out" | logAndCat "${ps_cmd_line[@]} | sort -k3,3nr" >"${store_file_prefix}$((update_round_num + 1))_ps"
    fi

    if ((count > 0)); then
        echo "$ps_out" | head -n "${count}"
    else
        echo "$ps_out"
    fi
}

# top with output field: thread id, %cpu
__top_threadId_cpu() {
    # DO NOT combine var java_pid_list declaration and assignment, because its value is supplied by subshell.
    local java_pid_list
    # shellcheck disable=SC2086
    java_pid_list="$(ps $ps_process_select_options -o pid --no-headers)"
    [ -n "$java_pid_list" ] || __die_when_no_java_process_found
    # shellcheck disable=SC2086
    java_pid_list="$(echo $java_pid_list | tr ' ' ,)" # join with ,

    # 1. sort by %cpu by top option `-o %CPU`
    #    unfortunately, top version 3.2 does not support -o option(supports from top version 3.3+),
    #    use
    #       HOME="$tmp_store_dir" top -H -b -n 1
    #    combined
    #       sort
    #    instead of
    #       HOME="$tmp_store_dir" top -H -b -n 1 -o '%CPU'
    # 2. change HOME env var when run top,
    #    so as to prevent top command output format being change by .toprc user config file unexpectedly
    # 3. use option `-d 0.5`(update interval 0.5 second) and `-n 2`(update 2 times),
    #    and use second time update data to get cpu percentage of thread in 0.5 second interval
    # 4. top v3.3, there is 1 black line between 2 update;
    #    but top v3.2, there is 2 blank lines between 2 update!
    local -a top_cmd_line=(top -H -b -d "$cpu_sample_interval" -n 2 -p "$java_pid_list")
    # DO NOT combine var ps_out declaration and assignment, because its value is supplied by subshell.
    local top_out
    top_out=$(HOME="$tmp_store_dir" "${top_cmd_line[@]}")
    if [ -n "$store_dir" ]; then
        echo "$top_out" | logAndCat "${top_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_top"
    fi

    # DO NOT combine var result_threads_top_info declaration and assignment, because its value is supplied by subshell.
    local result_threads_top_info
    result_threads_top_info=$(
        echo "$top_out" | awk '{
            # from text line to empty line, increase block index
            if (previousLine && !$0) blockIndex++
            # only print 4th text block(blockIndex == 3), aka. process info of second top update
            if (blockIndex == 3 && $1 ~ /^[0-9]+$/)
                print $1, $9  # $1 is thread id field, $9 is %cpu field
            previousLine = $0
        }'
    )
    [ -n "$result_threads_top_info" ] || __die_when_no_java_process_found

    echo "$result_threads_top_info" | sort -k2,2nr
}

__complete_pid_user_by_ps() {
    # ps output field: pid, thread id(lwp), user
    # shellcheck disable=SC2206
    local -a ps_cmd_line=(ps $ps_process_select_options -wwLo 'pid,lwp,user' --no-headers)
    # DO NOT combine var ps_out declaration and assignment, because its value is supplied by subshell.
    local ps_out
    ps_out="$("${ps_cmd_line[@]}")"
    if [ -n "$store_dir" ]; then
        echo "$ps_out" | logAndCat "${ps_cmd_line[@]}" >"${store_file_prefix}$((update_round_num + 1))_ps"
    fi

    local idx=0 threadId pcpu output_fields
    while read -r threadId pcpu; do
        ((count <= 0 || idx < count)) || break

        # output field: pid, threadId, pcpu, user
        output_fields="$(echo "$ps_out" |
            awk -v "threadId=$threadId" -v "pcpu=$pcpu" '$2==threadId {
                print $1, threadId, pcpu, $3; exit
            }')"
        if [ -n "$output_fields" ]; then
            ((idx++))
            echo "$output_fields"
        fi
    done
}

# output format is same as function findBusyJavaThreadsByPs
findBusyJavaThreadsByTop() {
    __top_threadId_cpu | __complete_pid_user_by_ps
}

printStackOfThreads() {
    local idx=0 pid threadId pcpu user threadId0x
    while read -r pid threadId pcpu user; do
        threadId0x="0x$(printf %x "${threadId}")"

        ((idx++))
        local jstackFile="${store_file_prefix}$((update_round_num + 1))_jstack_${pid}"
        [ -f "${jstackFile}" ] || {
            # shellcheck disable=SC2206
            local -a jstack_cmd_line=("$jstack_path" ${force} $mix_native_frames $more_lock_info ${pid})
            if [ "${user}" == "${USER}" ]; then
                # run without sudo, when java process user is current user
                logAndRun "${jstack_cmd_line[@]}" >"${jstackFile}"
            elif [ $UID == 0 ]; then
                # if java process user is not current user, must run jstack with sudo
                logAndRun sudo -u "${user}" "${jstack_cmd_line[@]}" >"${jstackFile}"
            else
                # current user is not root user, so can not run with sudo; print error message and rerun suggestion
                redPrint "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
                redPrint "User of java process($user) is not current user($USER), need sudo to rerun:"
                yellowPrint "    sudo $(printCallingCommandLine)"
                normalPrint
                continue
            fi || {
                redPrint "[$idx] Fail to jstack busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user})."
                normalPrint
                rm "${jstackFile}" &>/dev/null
                continue
            }
        }

        bluePrint "[$idx] Busy(${pcpu}%) thread(${threadId}/${threadId0x}) stack of java process(${pid}) under user(${user}):"

        if [ -n "$mix_native_frames" ]; then
            local sed_script="/--------------- $threadId ---------------/,/^---------------/ {
                /--------------- $threadId ---------------/b # skip first separator line
                /^---------------/d # delete second separator line
                p
            }"
        elif [ -n "$force" ]; then
            local sed_script="/^Thread ${threadId}:/,/^$/ {
                /^$/d; p # delete end separator line
            }"
        else
            local sed_script="/ nid=${threadId0x} /,/^$/ {
                /^$/d; p # delete end separator line
            }"
        fi
        {
            sed "$sed_script" -n "${jstackFile}"
            echo
        } | tee ${append_file:+-a "$append_file"} ${store_dir:+-a "${store_file_prefix}$PROG"}
    done
}

################################################################################
# Main
################################################################################

main() {
    local update_round_num
    # if update_count <= 0, infinite loop till user interrupted (eg: CTRL+C)
    for ((update_round_num = 0; update_count <= 0 || update_round_num < update_count; ++update_round_num)); do
        ((update_round_num > 0)) && sleep "$update_delay"

        [[ -n "$append_file" || -n "$store_dir" ]] && headInfo |
            tee ${append_file:+-a "$append_file"} ${store_dir:+-a "${store_file_prefix}$PROG"} >/dev/null
        ((update_count != 1)) && headInfo

        if [ "$cpu_sample_interval" == 0 ]; then
            findBusyJavaThreadsByPs
        else
            findBusyJavaThreadsByTop
        fi | printStackOfThreads
    done
}

main